Human defensin is a family of cationic antimicrobial peptides in human being. During the last two decades a series of endogenous alpha-and beta-human defensins have been discovered. They are important components of the first barrier in human's body against the invasion of various microorganisms, and they are thought to play an important role in linking the innate and adaptive defense system of human being. The recent advances in the research of human defensins were reviewed, including their discovery, molecular and genetic properties, expression regulation, and mechanisms of antimicrobial activity. The possibility to produce human defensins via genetic engineering was also discussed. And the application outlook of human defensins in medicine and curing patients infected with antibiotics-resistant microbials was presented.